Multifactorial telehealth care pregnancy and birth monitoring

ABSTRACT

The invention provides a system for monitoring a fetus in a pregnant woman, and/or the maternal health risk for pregnancies complicated by such as pre-eclampsia and hypertensive disorders. The system comprises a portable or wearable unit that can be worn by the pregnant woman, preferably so as to allow monitoring during daily life, e.g. in the form of an adhesive patch. The portable unit has a sound sensor, e.g. a microphone or accelerometer, to be positioned on the skin of the abdominal area of the pregnant woman so as to detect a vascular sound from umbilical arteries of the fetus or from the uterine arteries of the pregnant woman. The sound sensor is functionally connected to a processing unit which executes a processing algorithm on the captured vascular sound and extracts a signal parameter accordingly, e.g. the Pulsatility Index. The processing unit then communicates the signal parameter, e.g. using an audio signal, a visual display or by means of a wired or a wireless data signal. Some embodiments include one or more additional sensors, such as a sensor for detecting fetal electrocardiographic signals, and/or a sensor for detecting uterus electromyographic activity. Especially, the sound sensor and such additional sensor(s) may be arranged within one adhesive patch or several adhesive patches.

FIELD OF THE INVENTION

The present invention relates to field of medical devices, morespecifically such as telehealth care systems and pregnancy and birthmonitoring equipment. Especially, the invention provides a method andsystem for monitoring a fetus in the uterus of a pregnant women bymonitoring the state of the blood flow between the fetus and theplacenta by means of detecting blood flow in the umbilical arteriesand/or by monitoring the state of the perfusion of the uterus bydetecting blood flow in the uterine arteries.

BACKGROUND OF THE INVENTION

Caretaking of pregnant women in the group at risk for premature birthcontinues to be a huge clinical challenge being one of the main reasonsfor neonatal morbidity and mortality.

In the clinic, the growth of the fetus is normally estimated based on asimple distance measure of the pregnant woman's abdomen. This onlyprovides a rough measure of the growth of the fetus, and in case anyabnormal development is detected, the fetus has most likely sufferedfrom an abnormal development during several weeks before it is detected.

Once the pregnant woman is categorized as belonging to the high riskgroup for impaired growth other methods exist for monitoring thedevelopment of the fetus. A sufficient blood flow to the uterus andbetween the fetus and the placenta is vital for the fetus to develop.Thus, detection of any abnormal blood flow in the uterine arteries andthe umbilical arteries is important with respect to monitoring the stateof the fetus. This is possible by means of Doppler measurements, usingultrasound scanning equipment, to examine arterial blood flow. Hereby,e.g. the Pulsatility Index (PI) can be determined, and thus compared toa tabulated threshold value in order to assist the medical staff at theclinic in determining if the blood supply to the fetus is normal or ifany action is required. Ultrasound scanning for determination of uterineand umbilical arterial blood flow is used in cases such as: IntraUterine Growth Restriction (IUGR), twin pregnancy, maternalhypertension, maternal pre-eclampsia, maternal diabetes, and womenpregnant after In Vitro Fertilization (IVF).

Many women, being categorized as belonging to the high risk group,become anxious and many of those women either contact the clinic orhospital at regular intervals to ask for examination, and many women arefinally hospitalized, e.g. during weeks, in spite the fact that theirfetus has a normal development. Thus, there is a need for a solution toallow this group of woman to be monitored more closely during at least apart of their pregnancy without the need for hospitalization.

For pregnant women diagnosed with such as pre-eclampsia or hypertensivedisorders the feto-placental circulation is affected as the maternalstate of pre-eclampsia or hypertension worsens, therefore there is aneed for a system to monitor the maternal health risk during pregnancy.

SUMMARY OF THE INVENTION

Following the above description, it may be seen as an object of thepresent invention to provide a system for monitoring a fetus in apregnant woman and the maternal health risk for pregnancies complicatedby such as pre-eclampsia and hypertensive disorders which is suitablefor low-cost implementation and more continuously monitoring without theneed for skilled personnel to perform an examination.

In a first aspect, the invention provides a system for monitoring apregnant woman or a fetus in a pregnant woman, and/or the maternalhealth risk for pregnancies complicated by such as pre-eclampsia andhypertensive disorders.

The system comprises

a portable unit arranged to be carried by the pregnant woman, theportable unit comprising at least one sound sensor arranged for beingpositioned on the skin of the abdominal area and arranged to detect avascular sound from a uterine artery or from an umbilical artery of afetus present in the pregnant woman's uterus and to generate a firstsignal accordingly, and

a processing unit functionally connected to receive the first signal,wherein the processing unit is arranged to execute a first processingalgorithm on the first signal so as to extract at least a first signalparameter accordingly, and wherein the processing unit is arranged tocommunicate the at least first signal parameter.

Such system is suitable for monitoring the maternal vasculatory state inrelation to the pregnancy, and thus the system can serve to monitor thehealth state of the pregnant woman as well as the fetus. The system isadvantageous since the portable or wearable unit, e.g. in the form of anadhesive patch, can be worn by the pregnant woman during several hours,days or even weeks, where the vascular sounds from the uterine arteriesor the umbilical arteries can be continuously monitored or at leastmonitored at regular intervals. The processing unit can be integrated inthe wearable unit, e.g. within an adhesive patch, or the processing unitcan be constituted by a separate device worn in a belt or the like.Certain embodiments can serve as a monitor system to be worn in dailylife, and during the birth phase, the system can eliminate or at leastpartly replace existing monitoring systems.

The system can also be used to provide an early diagnosis of pregnancytoxaemia.

The invention is based on the insight, that it is possible to detectvascular sound from the uterine arteries and the umbilical arteries byusing a sound sensor in the form of a microphone or an accelerometer tocapture sound in the such as in the frequency range 50-5000 Hz on theskin of the abdominal area of the pregnant woman. Compared to the muchmore complicated Doppler ultrasound equipment, it is possible to providea system with at least the sound sensor in a portable or wearable unitso as to allow continuous monitoring of at least one parameter relatedto the blood flow in the uterine arteries or the umbilical arteries. Inpractice, Doppler ultrasound measurement of blood flow cannot beperformed without skilled persons being present and thus cannot beperformed without the pregnant woman being present at a clinic or at ahospital. Even if not performed often, it may be argued that theultrasound signals constitute a health risk for the fetus, whereas soundrecording on the surface of the skin can be performed very often, e.g.continuously, without any health risk.

With the system, the pregnant woman can be monitored while living anormal life at home and still having the feeling that she is taken careof, since the system can immediately give an alarm in case anyabnormality in the blood flow is detected. The processing unit itselfmay be capable of triggering an alarm based on the at least first signalparameter, e.g. a calculated Pulsatility Index (PI), which is comparedto a tabulated threshold value and which is considered to be outside anormal range. For example, the processing unit may itself have anacoustic or visual or vibrator alarm, or the processing unit may send amessage to the pregnant woman's mobile phone.

In some tele-healthcare embodiments, the processing unit communicatesthe at least first parameter, e.g. PI, via e.g. a home Personal Computervia the internet to a server at the hospital. Hereby, the medical staffat the hospital can monitor vital data for the patient continuously orat regular intervals, and e.g. the history of vital parameters may betracked and stored for later use. Hereby, it is possible to quicklydetect any abnormality at an early state, which significantly improvesthe chance of successful treatment without either the fetus or thepregnant woman suffering.

Still further, the system is advantageous also for the pregnant woman towear during the birth phase, where the uterine arterial blood flow andthe umbilical arterial blood flow provide additional knowledge regardingthe health status of the fetus. Especially, in embodiments includingalso EMG as well as fetal ECG sensors integrated in an adhesive patch tobe placed on the abdominal area of the pregnant woman. Thus, the mostvital parameters in the birth phase can be monitored in an easy waywithout the need for any additional sensor equipment, and especiallyinvasive electrodes on the fetus may be avoided. Further, the system isadvantageous for the pregnant woman to wear during surgery, especiallyduring caesarean section. Thus. there is no need for additionaltechnology to monitor the fetal condition during such surgery.

In one embodiment, the wearable unit further comprises at least onesensor arranged to detect an electromyographic (EMG) activity of thepregnant woman's uterus and to generate a second signal accordingly, andwherein the processing unit is functionally connected to receive thesecond signal. Such EMG sensor is advantageous for monitoring anyabnormal pre term myometrial activity in the uterus during the pregnancyat an early stage, so as to be able to intervene and possibly avoid preterm birth. However, the EMG sensor is also advantageous in the birthphase, where the myometrial activity in the uterus is important fordetermining the intrapartal status.

In one embodiment, the wearable unit further comprises at least onesensor (S3) arranged to detect an electrocardiographic (ECG) signal fromthe fetus in the pregnant woman's uterus and to generate a third signalaccordingly, and wherein the processing unit is functionally connectedto receive the third signal. Hereby it is possible to monitor forabnormalities in the ECG of the fetus which can be used to monitor thehealth state of the fetus in the pre-birth phase and during the birthphase, e.g. by monitoring pulse rate in order to detect any tachycardiaor bradycardia. Further, knowledge of the fetal ECG also allowsmonitoring of other parameters of the fetal ECG, such as monitoring ofthe ST segment in order to detect possible ST elevation.

In a preferred embodiment, the wearable unit comprises both the soundsensor, an EMG sensor and an ECG sensor, as just described. Especially,all of the mentioned three sensors may be placed within an adhesivepatch. Preferably, the processing unit is arranged to process all of thefirst signal, the second signal and the third signal and to generate acombined signal parameter in response to all of the first, second andthird signals. Hereby, a combined measure or status of the healthcondition of the fetus is possible, and it is possible to generate analarm in case abnormalities are detected.

In general, the portable or wearable unit may comprise an adhesive patchwithin which the at least one sound sensor is arranged so as to allowthe sound sensor to be in contact with the skin of the abdominal area ofthe pregnant woman. Especially, the adhesive patch may have asemi-circular shape and be suited for being positioned on the skin ofthe abdominal area of the pregnant woman, medially from the umbilicus.However, the portable or wearable unit in which the sound sensor isplaced may alternatively be in the form of a small device arranged forpositioning on the abdominal area of the pregnant woman by means of astrap, a belt or a plaster etc.

In some embodiments, the system comprises two or more adhesive patchesarranged for position on respective areas of the abdomen of the pregnantwoman, wherein each adhesive patch has at least one sound sensorarranged therein which is functionally connected to the processing unit.Such embodiments are advantageous, since sensor patches can bepositioned at several positions, e.g. on both sides of the abdominalarea, so as to be able to capture uterine or umbilical artery soundindependent of the actual position of the fetus.

The portable or wearable unit may comprise a plurality, e.g. two, threeor even more sound sensors arranged at different positions, e.g. withinan adhesive patch or several adhesive patches, so as to provide a betterchance of catching the vascular sound from the uterine arteries and theumbilical arteries independently of the position of the fetus. Hereby,the processing unit may be arranged to compare the quality of the soundsignals from the plurality of sensors to process the signal from thesound sensor providing the highest quality of vascular sound.

Furthermore, each sound sensor may be accompanied by an additionalmicrophone, a “room microphone”, where the sound sensor is recording thesound from within the abdominal wall and the additional microphone islocated so as to record sound from the environment. Preferably, theprocessing unit is then arranged to perform adaptive filtering of thesignal from the sound sensor and thereby eliminate noise from thesurroundings in the signal which is further processed. Especially, suchnoise cancellation processing may be based on a noise cancellationalgorithm comprising Wiener-filtering. With a “room microphone” andsuitable noise cancellation processing, it is possible to obtain a moreprecise result of the processing, and it is possible to detect therather weak sound or accelerometer signals and thus perform themonitoring even in environments with a significant noise level, such asin the traffic or the like.

The processing unit may form part of the portable or wearable unit. E.g.the processing unit may be arranged within an adhesive patch, especiallywithin the same patch in which the sound sensor is also placed. Thesound sensor, the necessary analog electronic circuits,analog-to-digital converter, a processor running the first processingalgorithm, and a battery arrangement to drive all of these elements, maybe arranged within the adhesive patch. The processing unit within thepatch may then be able to communicate the first signal parameter andpossibly more data to an external device, e.g. a mobile phone etc. via awire or wirelessly using e.g. Bluetooth technology or the like.

Alternatively, the processing unit may be implemented as one of: aportable device, such as a mobile phone, a Personal Computer, and aserver system. In such systems, the first signal from the sound sensoris preferably analog-to-digitally converted and transmitted by wire orwirelessly in data packets to the external device which then executesthe first processing algorithm on the data packets and generates thefirst signal parameter. Especially, the portable device may be a smallbattery driven device arranged for being worn by the pregnant woman in abelt or a strap or in a pocket. However, the external device may also bea smart phone with the first processing algorithm implemented as anapplication to be run on the smart phone.

In some embodiments a smart phone, or a similar device, with a suitableapplication, is arranged to receive data from the portable unit by meansof a short-range wireless communication e.g. Bluetooth, or the like.Thus, in such embodiments, the portable unit, e.g. in the form of anadhesive patch, only needs to include the necessary electronic meansarranged for receiving signals from the sensors, e.g. microphone andpossibly other sensors, and to communicate those signals to the smartphone via the short-range wireless communication link. The smart phoneapplication serves to perform the entire first processing algorithm,thus utilizing the processing power in the smart phone, thereby allowingthe processing capabilities in the portable or wearable unit to belimited, thereby allowing a low cost and low power processor to be used.However, it is to be understood that several possibilities for thestructure of the data to be communicated between the portable orwearable unit and the smart phone. To reduce the amount of data to becommunicated to the smart phone, part of or even all of the firstprocessing algorithm may be performed by processing circuit included inthe portable or wearable unit. The smart phone can be used for thecommunication of the signal parameter to the pregnant woman by means ofaudio and/or video signals. However, the portable or wearable unit mayalso include audible and/or video means arranged to provide the womanand/or a health care practitioner with the result of the monitoring,e.g. in the form of an audible or visible warning, if an abnormalsituation is detected.

In some embodiments, the portable unit collects data from the soundsensor for a period of time, e.g. several hours or one or more days.These data are then transferred to another device in which theprocessing unit is implemented, e.g. a Personal Computer or the like,e.g. by data transfer from the portable unit via a USB interface or thelike.

The sound sensor may be a sound sensor as known within the art ofelectronic stethoscopes for sensing heart and lung sounds, e.g. as anexample of a specific product: 3M Littman® Electronic Stethoscope Model4000. Other type of microphones could be used, however it is preferredthat the sound sensor used has a low noise floor, preferably a noisefloor which is below 40 dB Sound Pressure Level (SPL, i.e. soundpressure level re. 20 μPa), more preferably below 30 dB SPL, morepreferably below 25 dB SPL. The sound sensor is preferably suited tocover at least the frequency range 100-1000 Hz, more preferably 50-5000Hz. It is preferred that the microphone is shaped and suited for andfixed to the woman, so as to be in close contact with the abdominalskin. As mentioned, the sound sensor can be in the form of anaccelerometer as an alternative or in addition to a microphone.

In preferred embodiments, the first processing algorithm is arranged toband-pass filter the first signal and generate a band-pass filteredfirst signal accordingly. The band-pass filter may have a bandwidthwithin 50-5000 Hz. The lower cut-off frequency of the band-pass filtermay be within the range 30-200, preferably within 50-150 Hz, or within50-100 Hz. The upper cut-off frequency may be within the range 800-20000Hz, preferably within 1000-10000 Hz, such as within 1500-5000 Hz. Inspecial embodiments, the band-pass filter may have a bandwidth of suchas 50-4000 Hz, or 50-3000 Hz, or 80-2000 Hz, or 100-1000 Hz, or 200-800Hz. It is to be understood that the entire band-pass filtering effect orat least a part of it may be provided by the acoustical and/ormechanical design of the sound sensor. Thus, it may be preferred to usea specially designed sound sensor with a frequency characteristicsserving to suppress sound outside the most important frequency range,which may eliminate or at least supplement the need for a band-passfilter as part of the processing.

Subsequently, the first processing algorithm is preferably arranged todetect a signal envelope, such as by rectifying the band-pass filteredfirst signal and to generate a rectified first signal accordingly.Subsequently, the first processing algorithm is preferably furtherarranged to low-pass filter the rectified first signal and to generate alow-pass filtered first signal accordingly. The low-pass filter may havea cut-off frequency within the interval 1-20 Hz, such as within theinterval 2-15 Hz, such as within the interval 3-10 Hz, such as withinthe interval 4-8 Hz. Subsequently, the first processing algorithm ispreferably arranged to extract a first signal parameter comprising atleast one of: a Pulsatility Index, a rise time of the sound from thearteries, and a decay time of sound from the arteries, venous flow, andclosure timing of the aortic valve, thereby the end of systole and thestart of the diastole. An intermediate step of providing a signalenvelope may be performed before the step of extracting the first signalparameter.

It is to be understood that alternative signal processing algorithms maybe performed on the signals from the sound sensor to derive signalparameters related to the uterine arterial blood flow or the umbilicalarterial blood flow.

In some embodiments, the processing unit is arranged to perform analgorithm serving to process recorded sound from the sound sensor withthe purpose of determining if the recorded sound is sound from anumbilical artery or sound from a uterine artery. This can be determinedfrom the position of the sound sensor and/or from the heart rate andother characteristics of the sound from the blood flow. It may bepreferred to adjust one or more parameters of the further signalprocessing depending on whether the recorded sound emanates from anumbilical artery or from a uterine artery.

The system may be arranged to compare the first signal parameter to athreshold and trigger an alarm event in case the first signal parameterexceeds the threshold, such as an alarm event comprising at least oneof: a visual alarm signal, an acoustic alarm signal, and a tactile alarmsignal. The system may be arranged to alarm the pregnant woman, and/ormedical staff, and thus the alarm may be communicated to severallocations, e.g. wirelessly such as via the internet and/or a mobilephone net of the like.

The at least one sound sensor may comprise at least a microphone and/oran accelerometer. Preferably, the at least one sound sensor has a noisefloor equivalent to a Sound Pressure Level of less than 40 dB re. 20μPa, such as a Sound Pressure Level of less than 30 dB re. 20 μPa. Thisis found suitable to obtain a reliable detection of the weak arterysounds.

The system may comprise a plurality of sound sensors functionallyconnected to the processing unit, wherein the plurality of sound sensorsare arranged for respective positions on the abdomen. This allows thesystem to function at different positions of the fetus in the uterus.Especially, the processing unit may be arranged to process signalsreceived from the plurality of sound sensors and to calculate aparameter, e.g. a measure of signal-to-noise ratio, for each soundsensor, and to select which of the plurality of sound sensors to use formonitoring, based on said calculated parameter. Thus, the sound sensordelivering the best signal can be selected for the actual monitoring.Especially, the processing unit may be arranged to re-calculate theparameter for each sound sensor, so as to allow an updated selection ofwhich of the plurality of sound sensors to use for monitoring. Hereby,the system will automatically adapt to e.g. different positions of thefetus, a damaged microphone or the like.

In one embodiment, the system comprises at least one microphone arrangedto detect environmental sound near the sound sensor, wherein the atleast one microphone is functionally connected to the processing unit,and wherein the processing unit is arranged to cancel influence fromenvironmental noise in the signal from the sound sensor based on aninput received from the at least one microphone. This allows themonitoring system to work in noisy environments. The processing unit maybe arranged to cancel influence from environmental noise in the signalfrom the sound sensor by means of a noise cancellation algorithmcomprising Wiener-filtering. Additional or alternative noise calculationalgorithm such as known in the art may be selected. In case more soundsensors are used, it may be preferred that each sound sensor has itrespective microphone to capture environmental noise placed in closeproximity to each sound sensor, in order to provide the best possibleinput to the noise cancellation algorithm.

The first processing algorithm may be arranged to at least high-passfilter the first signal and generate a high-pass filtered first signalaccordingly, wherein the high-pass filter has a cut-off frequency withinthe range 50-200 Hz, such as within 50-150 Hz, such as 100-200 Hz. Suchinitial high-pass filtering of the signal received from the sound sensorserves to provide a clean signal for further processing. It is to beunderstood that the exact cut-off frequency of the high-pass filter maybe selected within the given interval without significant differentresult, the same applied to the slope of the high-pass filter which maybe selected in dependence of the used sound sensor and other factors. Itmay in addition be preferred to low-pass filter the first signal, andthus provide a band-pass filter, as already mentioned.

In a second aspect, the invention provides a method for monitoring afetus in a pregnant woman and/or for monitoring the maternal risk statein pregnancies complicated by such as pre-eclampsia or hypertensivedisorders. The method comprises

detecting a vascular sound from a uterine artery or from an umbilicalartery of a fetus present in the pregnant woman's uterus by means of atleast one sound sensor arranged on the skin of the abdominal area, theat least one sound sensor being arranged in a portable or wearable unitarranged for being carried by the pregnant woman,

generating a first signal according to the detected vascular sound,

executing a first processing algorithm on the first signal so as toextract at least a first signal parameter accordingly, and

communicating the at least first signal parameter.

The first and second aspects may each be combined with any of the otheraspects. These and other aspects of the invention will be apparent fromand elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE FIGURES

Embodiments of the invention will be described in more detail in thefollowing with regard to the accompanying figures. The figures show oneway of implementing the present invention and is not to be construed asbeing limiting to other possible embodiments falling within the scope ofthe attached claim set.

FIG. 1 shows a block diagram of an embodiment,

FIG. 2 shows a block diagram of another embodiment,

FIG. 3 shows an example of a patch with a built-in sound sensor to beplaced on the abdomen of the pregnant woman,

FIG. 4 shows an example of another patch with built-in sound sensors aswell as EMG and ECG sensors,

FIG. 5 shows a block diagram of a telehealth care embodiment,

FIG. 6 shows preferred steps of the processing of the sound signal toderive a meaningful signal parameter indicative of the arterial bloodflow, and

FIGS. 7a-7d illustrate different steps of the preferred processing stepsof FIG. 6 by graphs showing time data at different stages of theprocessing.

DETAILED DESCRIPTION OF AN EMBODIMENT

FIG. 1 shows a simple block diagram of an embodiment. A vascular soundsignal VS from an umbilical artery or a uterine artery is detected by asound sensor S1 placed on the skin of the abdominal area of the pregnantwoman. The sound sensor S1 preferably comprises a microphone arranged tosense low amplitude signals ranging from 50-5000 Hz, or at least up to1000 Hz, preferably up to 2000 Hz. A requirement for the sound sensor islow inherent (thermal) noise and a high sensitivity in order to recordthe weak vascular sounds. A noise floor below 30 dB SPL is preferred.

The sound sensor S1 is placed within a portable unit here shown as awearable unit WU to be worn by the pregnant woman, and which ispreferably arranged with some kind of attachment or fixing means so asto be able to maintain the sound sensor S1 in the correct positionduring the pregnant woman performing normal daily activities or alsoduring birth. The wearable unit WU may include various types of fixingmeans serving this purpose such as straps, belts, plaster etc.Especially, the wearable unit WU may comprise an adhesive patch with thesound sensor S1 arranged within the patch so as to provide a watertightcavity for the sound sensor S1 and necessary battery and electroniccircuits connected to the sound sensor S1 in order to provide anelectric output signal in accordance with the sensed sound. The systemmight also comprise several patches as described above, where each patchcontains a sound sensor for recording of the sound signal from itsposition on the abdominal wall. The patches may be wired together to thewearable unit. This or these electric output signal(s) is/are applied,wired or wirelessly, to a processing unit P which executes a firstprocessing algorithm PA1.

The processing algorithm PA1 preferably operates on a time frame of thesound signal from the sound sensor S1, e.g. frames of 1-60 seconds, suchas 5-10 seconds, and calculates a first signal parameter SP1 indicativeof the umbilical and/or uterine arterial blood flow, such as calculatinga measure of the Pulsatility Index (PI), possibly more signal parametersmay be calculated. Further, the processing unit P can be arranged toevaluate the first signal parameter SP1 with a tabulated thresholdvalue, and communicate an alarm signal AL in case the normal thresholdvalue is exceeded. The processing unit may also be able to communicatethe first signal parameter SP1 to external units. Especially, the firstsignal parameter SP1 may be communicated to an external server or thelike. E.g. the first signal parameter SP1 may be presented in a graph ata display for medical staff at the hospital where the first signalparameter is presented versus time for e.g. one hour, one day or severaldays, so as to allow the medical staff to monitor the health state ofthe fetus and diagnose the pregnant woman.

FIG. 2 shows another embodiment where the element described in relationto FIG. 1 are also present, but in this embodiment, the wearable unit WUalso comprises a sensor S2 arranged to sense an electromyographic EMGsignal from the uterus, and a sensor S3 arranged to sense anelectrocardiographic signal from the fetus inside the uterus. Both ofthese sensors S2, S3 are also placed on the skin of the abdomen of thepregnant woman. Time signals from all of the three different sensors S1,S2, S3 are applied to the processing unit P which executes a processingalgorithm PA handling data from all three sensors S1, S2, S3 andgenerates a set of signal parameters SP, preferably at least one foreach sensor S1, S2, S3, in response to the time signals from the sensorsS1, S2, S3. In practice different algorithms are run for each of thesensors S1, S2, S3, and thus different signal parameters SP are derivedaccordingly. The processing unit P may be arranged to take into accountall signal parameters P and perform a combined evaluation and possiblygenerate an alarm signal AL in case an abnormal status is detected.

FIG. 3 shows a sketch of a pregnant woman and a wearable unit WUimplemented as an adhesive path which is semi-circular or C-shaped inorder to fit a lower abdominal area, e.g. the patch may be positionedabout 10-15 cm below the umbilicus with direction towards the pelvicbone for optimal sound capturing. A sound sensor S1 is indicated withinthe patch. It is to be understood that preferably also a battery and thenecessary electronic circuit related to the sound sensor S1 are placedwithin the patch. However, in simple versions, the sound sensor S1 maybe connected to the external circuits via a wire, such as a wireconnected to other parts of the wearable unit WU, e.g. a small portabledevice suited for being placed in a belt, a strap, or in a pocket. Thepatch may be delivered together with a guidance, such as including atemplate that allows the pregnant woman to position and mount theadhesive patch herself.

FIG. 4 shows another version of the patch of FIG. 3. Here, two soundsensors S1, two EMG sensors S2, and two fetus ECG sensors S3 are placedwithin the patch of the portable or wearable unit WU. The two sensors ofeach type are placed at different positions so as to increase the chanceof successfully retrieve the desired signals, compared to only onesensor. Further, the processing unit P connected to the sensors S1, S2,S3, including a battery, is also placed within the patch of the wearableunit WU. The processing unit P is arranged to wirelessly communicate adata signal D to a portable device PD, e.g. a mobile phone, a smartphone device, or the like, by means of a short-range wirelesscommunication link such as Bluetooth. The data signal D may include oneor more signal parameters extracted based on the signals from thesensors S1, S2, S3.

The portable device PD, e.g. a smart phone, can then be used to processthe data signal D and to communicate the result—e.g. using text andgraphics on the display of the smart phone, such as “All OK” or “Pleasecontact the clinic for a check”. In case serious problems are detected,an acoustic or visual alarm may be communicated to the pregnant woman,utilizing the audio and video capabilities of the smart phone. Further,the smart phone may run an application which automatically communicatesparts of or all of the performed results to the hospital, so as to allowa medical doctor to further analyse the results.

In one specific embodiment, the sound sensor in the form of one or moremicrophones or accelerometer are positioned within an adhesive patch,with the processing unit arranged also within this patch. Thisprocessing unit may perform all processing required, or it may merelyserve the purpose of receiving the microphone signals and transmittingit further in a wireless signal, e.g. to a mobile phone or the likewhich has the processing power and is programmed to perform furtherprocessing. In case the processing unit within the patch includesfurther processing tasks, the processing unit may in wireless formtransmit only in case an abnormal situation is detected, e.g. to amobile phone or the like. Thus, the mobile phone may in such case beprogrammed to display: “Please contact hospital or doctor”.Alternatively, the processing unit within the patch may transmit furtherdetailed data, e.g. a calculated PI, e.g. at regular intervals. Suchembodiment can be used for home monitoring, when the pregnant woman ishospitalized, or during the birth phase. In addition to the uterineartery or umbilical artery sound input, the patch may include also anEMG sensor to monitor for (too early) birth pangs, and an ECG sensor tomonitor the pulse rate of the fetus. Hereby, the system will be suitedboth for home monitoring and also as monitoring unit to be used in birthphase.

FIG. 5 shows a block diagram of a tele healthcare system embodiment,where a system including a wearable unit WU with a sound sensor and aprocessing unit P communicate a first signal parameter SP1, e.g. a PIvalue, wirelessly to a Personal Computer PC in the pregnant woman'shome, and the Personal Computer PC is then connected and supplied withsoftware arranged to transmit data to a hospital server HS via theinternet, such as at regular intervals, e.g. once a day etc. Hereby, thepregnant woman can live a normal life, but still be monitored at aregular basis by a medical staff which can receive relevant informationregarding the monitored umbilical and/or uterine arterial blood flow.Further, the hospital server HS may run software monitoring the incomingdata according to a predetermined evaluation algorithm and generatesalarm signal in response, if abnormalities are detected.

FIG. 6 shows a block diagram of a preferred signal processing to beapplied to sound signal SS captured by the sound sensor in order toderive one or more signal parameters indicative of the umbilical and/oruterine arterial blood flow. In a first step, the sound signal SS ispreferably band-pass filtered in a band-pass filter BPF with a band-passfrequency range of 50-5000 Hz or a more narrow filter, e.g. down to suchas 100-1500 Hz or even 200-800 Hz, e.g. implemented as a Chebychevtype-2, with a pass-band ripple of 1 dB, and with a stop-bandattenuation of more than 40 dB. Next, the signal is rectified RTF, andnext an envelope ENV of the rectified and filtered signal is extracted.Especially, the envelope may be obtained by low-pass filtering therectified signal, e.g. using a Chebychev type-2 filter, with a cut-offfrequency of 1-10 Hz, such as 4-8 Hz, e.g. 6 Hz, with a pass-band rippleof such as 2 dB, and a stop band attenuation of more than 40 dB. Fromthe resulting envelope, several parameters can be extracted. E.g. thePulsatility Index PI is one (calculated as peak/bottom ratios), arise-time and a decay-time of the pulses are other signal parameters ofinterest. There seems to be “dicrotic notches” on the falling edges ofthe envelope, which may also be used in further investigations.

It is to be understood that several additional or alternative signalprocessing algorithms may be performed, and there are several parametersto vary: frequencies of the band-pass filter, frequency of the low-passfilter, and also the frequency distribution and changes therein duringthe pulses, can be of interest.

FIGS. 7a-7d show examples of an 8 second sound signal at various stepsof a preferred signal processing algorithm just described. FIG. 7a showsthe raw sound signal picked up at the abdominal skin of a pregnantwoman, and the signal is presented as amplitude versus time. The pulserate, slightly above 60 beats per minute, is clearly seen. Altogether,the sound of the umbilical or uterine arteries reflects the state of thematernal blood supply to the placenta, the blood flow between theplacenta and the fetus, as well as events in the fetal cardiac cycle,i.e. the deceleration of blood, turbulence of the blood flow and theclosing of the fetal heart valves. FIG. 7b shows the signal afterband-pass filtering with a 200-800 Hz band-pass filter. FIG. 7c showsthe band-pass filtered signal after rectification, and finally FIG. 7dshows the signal envelope resulting from a 6 Hz low pass filtering. Theenvelope can be used, among others, to derive the PI.

To sum up, the invention provides a system for monitoring a fetus in apregnant woman, and/or the maternal health risk for pregnanciescomplicated by such as pre-eclampsia, and hypertensive disorders. Thesystem comprises a portable or wearable unit that can be worn by thepregnant woman, preferably so as to allow monitoring during daily life(home monitoring), e.g. in the form of an adhesive patch. The portableunit has a sound sensor, e.g. a microphone or accelerometer, to bepositioned on the skin of the abdominal area of the pregnant woman so asto detect a vascular sound from the uterine arteries and/or umbilicalarteries of the fetus. The sound sensor is functionally connected to aprocessing unit which executes a processing algorithm on the capturedvascular sound and extracts a signal parameter accordingly, e.g. thePulsatility Index. The processing unit then communicates the signalparameter, e.g. using an audio signal, a visual display or by means of awired or a wireless data signal. Some embodiments include one or moreadditional sensors, such as a sensor for detecting fetalelectrocardiographic signals, and/or a sensor for detecting uteruselectromyographic activity. Especially, the sound sensor and suchadditional sensor(s) may be arranged within one adhesive patch.

Although the present invention has been described in connection with thespecified embodiments, it should not be construed as being in any waylimited to the presented examples. The scope of the present invention isset out by the accompanying claim set. In the context of the claims, theterms “comprising” or “comprises” do not exclude other possible elementsor steps. Also, the mentioning of references such as “a” or “an” etc.should not be construed as excluding a plurality. The use of referencesigns in the claims with respect to elements indicated in the figuresshall also not be construed as limiting the scope of the invention.Furthermore, individual features mentioned in different claims, maypossibly be advantageously combined, and the mentioning of thesefeatures in different claims does not exclude that a combination offeatures is not possible and advantageous.

1.-29. (canceled)
 30. A portable unit configured to be carried by apregnant woman, the portable unit comprising: an adhesive patch; a soundsensor arranged in the adhesive patch so as to be positioned in contactwith the skin of an abdomen of the pregnant woman, the sound sensorbeing configured to capture vascular sound from a uterine artery or froman umbilical artery of a fetus present in the pregnant woman's uterus,wherein the portable unit is configured to transmit a wireless signalcomprising a representation of the captured vascular sound.
 31. Theportable unit of claim 30, wherein the representation of the capturedvascular sound comprises the captured vascular sound in an unmodifiedform.
 32. The portable unit of claim 30, the portable unit comprising afilter configured to filter the captured vascular sound, wherein therepresentation of the captured vascular sound comprises the filteredvascular sound.
 33. The portable unit of claim 32, wherein the filtercomprises a band-pass filter.
 34. The portable unit of claim 32, whereinthe filter comprises a low-pass filter.
 35. The portable unit of claim32, wherein the filtered vascular sound comprises a signal envelope ofthe captured vascular sound.
 36. The portable unit of claim 30, furthercomprising a microphone, the microphone being arranged to record soundfrom an environment around the pregnant woman, wherein the portable unitis configured to eliminate noise from the captured vascular sound by therecorded sound from the environment, thereby forming noise cancelledvascular sound, wherein the representation of the captured vascularsound transmitted by the portable unit comprises the noise cancelledvascular sound.
 37. The portable unit of claim 30, wherein the portableunit comprises two sound sensors arranged at different positions in theadhesive patch.
 38. The portable unit of claim 37, wherein the adhesivepatch is configured to position the two sound sensors on opposite sidesof the abdomen of the pregnant woman.
 39. The portable unit of claim 30,wherein the adhesive patch has a semi-circular shape.
 40. The portableunit of claim 30, wherein the sound sensor is configured to capturevascular sound in the frequency range 50-5000 Hz, and wherein therepresentation of the captured vascular sound comprises the capturedvascular sound in the frequency range 50-5000 Hz in an unmodified form,in a filtered form, or in a noise cancelled form.
 41. A method formonitoring a pregnant woman or a fetus in a pregnant woman, the methodcomprising: receiving a wireless signal, the wireless signal comprisinga representation of vascular sound from a uterine artery or an umbilicalartery of a fetus present in the pregnant woman's uterus; and processingthe wireless signal to extract a state of the maternal blood supply to aplacenta and/or blood flow between the placenta and the fetus.
 42. Themethod of claim 41, wherein the representation of vascular sound is asignal envelope of the vascular sound.
 43. The method of claim 41,wherein the method is implemented in a mobile phone.
 44. The method ofclaim 41, wherein the extracted state of the maternal blood supply to aplacenta and/or blood flow between the placenta and the fetus comprisesat least one of: a Pulsatility Index, a rise time of arterial sound, anda decay time of arterial sound, venous flow, and timing of a dicroticnotch.